I need to translate this data by sub-pixel distances which will inevitably involve interpolation. I can live with linear interpolation as the data is sampled quite finely. I am using imtransform to achieve this. The shifted-data need to be obtained only over the original grid. I want extrapolated locations to be zero.

Results are satisfactory but slow as this shifting happens in the inner-most loop. Can anyone suggest a method that involves direct indexing and hence would be faster? Any neat algorithm published in the literature for sub-pixel translation?